An Internet Protocol (IP) Multimedia Subsystem (IMS)-based VoLTE refers to an IMS-based voice service structured on an LTE network, transmits a voice through an IP packet and may enable a mobile phone to receive a sound frequency ranging from 50 to 7,000 Hz. Therefore, the quality of voice calls is greatly improved.
At present, for a mobile phone supporting VoLTE, many MBN (modem software configuration) files are configured for different countries and different operators. MBN is marketed by the Qualcomm Incorporated to meet modem software configuration solutions of multiple manufacturers, multiple network types and multiple purposes. After a 4th-Generation (4G) Subscriber Identity Module (SIM) card supporting a VoLTE function is inserted into a mobile phone and detected by a modem successfully, an Integrate Circuit Card Identity (ICCID) is acquired, and a correct Issuer Identification Number (HN) value is acquired according to the ICCID. The ICCID is solidified in the SIM card of the mobile phone and the HN is used to distinguish between different operators. An MBN list is searched for an MBN file for a corresponding operator according to the IIN, and then the MBN file is automatically loaded. After the MBN file is successfully loaded, the mobile phone may activate a configuration item related to the VoLTE function in the MBN file and registere on a VoLTE network.
However, in different countries or regions, SIM cards that support the VoLTE service are different. A length of the IIN obtained from the ICCID is usually 6 to 7 bits, and an MBN file for a corresponding operator may be queried by a mobile phone according to the IIN. However, the length of the IIN of the operating company in some countries (for example, “Reliance” in India) reachs 11 bits, which makes it impossible for a mobile phone to find a corresponding MBN file from the MBN list. Therefore, the existing method for querying the MBN file has a low success rate. Since an MBN file may not be loaded, registration on the VoLTE network may not be implemented and a user may not access the Internet and make a voice call.